Structural elements for an artificial ski slide



C- 31 1967 :SAO MAKI 3,350,092

STRUCTURAL ELEMENTS FOR AN ARTIFICIAL SKI SLIDE O MAb 43 Oct. 31, 1967|SAO MAK| 3,350,092

STRUCTURAL ELEMENTS FOR AN ARTIFICIAL SKI SLIDE Filed DSC. 14, 1964 2Sheets-Sheen 2 United States Patent C 3,350,092 STRUCTURAL ELEMENTS FORAN ARTIFICIAL SKI SLIDE Isao Maki, 85 Z-chome, Nihonbashihama-cho,Chun-ku, Tokyo, Japan Filed Dec. 14, 1964, Ser. No. 418,060 5 Claims.(Cl. 272-565) ABSTRACT F THE DISCLSURE This invention relates to anartificial slide for 'skiing made of a base sheet having thereon aplurality of relatively flexible needle-like projections made ofthermoplastic resinous material and molded into a unitary structure, theplurality of the needle-like projections being in at least two groups,the projections of which are somewhat different in height and disposedalternately.

-man The object of the present invention is to provide an improvedartificial slide for skiing, in which the sliding effect can becontrolled by -tilting the ski and sliding it in a longitudinal, lateralor oblique direction.

It is another object of the present invention to provide an improvedartificial slide for skiing, in which any undue slippage of the skiersski can be prevented. Y

These and other objects of the present invention will become apparentfrom the following detailed description taken in conjunction with theIaccompanying drawings wherein:

FIG. 1 is a perspective view of one structural element constructed inaccordance with the teachings of the invention with parts omitted;

FIG. 2 is a fragmental view, in vertical section, of the elementillustrated in FIG. l;

FIG. 3 is a top plan view of the element illustrated in FIGS. l and 2;

FIG. 4 is a bottom view of the element illustrated in FIGS. 1 through 3;

FIG. 5 is -a vertical section, showing the manner in which thestructural element is deformed when the associated ski is effecting aschuss;

FIG. 6 is a vertical section, showing the manner in which the structuralelement is deformed upon braking a ski; and

FIGS. 7, 8 and 9 are fragmentary views of modifications ofthe invention.

Referring now to FIGS. 1 through 4 of the drawings, a structural elementconstructed in accordance with the teachings of the invention includes abase sheet 10, for example, in the form `of a square having a lower,relatively smooth bottom face and an upper face having a plurality ofribs formed integrally thereon in a grid arrangement as best shown inFIG. 3. The ribs 20 serve to prevent the base sheet 10 from warping andalso serve to prevent any undue slip of the lower end of the skiersstock. It is to be understood that the base sheet may, if desired, haveany suitable shape other than the square shape as long as a plurality ofthe base sheets can continuously cover an area of a plane and that theribs may be disposed in -any other suitable arrangement as long as theyserve to prevent warping of the base sheet. For example, instead of thesquare shape the base sheet may have, for example, a rectangular,rhombic or trapezoidal shape, or an equilateral triangle, an isoscelestriangle, or a regular hexagon or the like. The element 10 furtherincludes a needle unit generally designated by the reference numeralconsisting of a multiplicity of relatively highly flexible needle-likeprojections extending upwardly from and substantially at right angles`to the plane of the upper face of the base sheet 10.

3,350,092 Patented Oct. 31, 1967 As shown in FIGS. l and 2, the needleunit 30 includes longer and shorter needle-like projections 31 and 32,respectively, disposed alternately as viewed in longitudinal, transverseand oblique directions, as shown in FIGS. 1 and 2.

According to the teachings of the invention, the structural element asabove' described is composed of any suitable thermoplastic resinousmaterial having a relatively high flexibility or pliability and moldedinto a unitary structure. The preferred materials for the element arepolypropylenes and polyethylenes. The use of the molding technique ispossible so that mass production can be used resulting in cheapelements. Also the use of the thermoplastic resinous materials leads toan advantage that the elements can be effectively washed with water and/or any suitable chemical for cleaning purpose. Further the presentelements are advantageous in that, even if any excessive force would beexternally applied to the elements, the same are not damaged due totheir flexibility and that they do not injure persons and articles.

Said plurality of needle-like projections are divided into two groups,one group comprising the needle-like projections 31 of larger heightland the other group comprising the needle-like projections 32 ofsmaller height, and said larger and smaller needle-like projections arearranged alternately in all longitudinal, transverse and obliquedirections of the rows, as shown in FIG. 3.

Preferably the needle-like projections 31 and 32 each have an enlargedroot portion integrally connected to the upper face of the base sheet 10and are tapered toward the free extremity with the latter somewhatround. With the needle-like projections shaped in the manner justdescribed, the material for the element is permitted to easily flow intoa mold during the injection molding operation.

The needle-like projections 31 and 32 should he disposed on the basesheet 10 close enough to prevent the front end portion of a skiers stockmoving on the elements to tend to forcedly project between any pair ofthe adjacent projections. In other words, the spacing between twoadjacent needle-like projections should be narrower than the diameter ofthe front end portion of the stock. This measure ensures the movingskiers stock against the danger that the stock slides directly along theupper faces of the aligned base sheets 10' due to a forced entrance ofthe stock extremity between the two adjacent needle-like projections.

In order for the structural elements 10` as above described to berigidly secured on a natural or artificial inclined foundation, the basesheet 10 is provided with marginal portions on the entire length of thesides thereof. More specifically, as clearly shown in FIGS. 2 through 4,the square base sheet 10 includes an Lashaped flange or marginal portion41 projecting outwardly from the two adjacent sides and another L-shapedflange or marginal portion 42 projecting outwardly from the remainingsides with the marginal portions perforated at 43. The marginal portion41 has its lower surface forming an extension of the lower face of thebase sheet 10 and the marginal portion 42 has its upper surface formingan extension of the-upper face of the sheet. The lower and uppersurfaces respectively of the marginal portions 41 and 42 are designedand constructed such that, when the marginal portion 42 of one element10 is superposed on the marginal portion 41 of the adjacent element, theupper and lower surfaces of the superposed marginal portion 42 and 41are flush with the upper and lower faces of the base sheets 10respectively. To this end, the unarginal portions are preferably a halfthe thickness of the base sheet.

It will be appreciated that, with the element aligned in the manner justdescribed, the perforations 43 on the marginal portion of one clementare registered with the associated perforations 43 on the superposedmarginal portion of the adjacent element.

In order to construct an artificial Gelande, a number of the structuralelements as above described are placed on a foundation such as shown atthe reference character D in FIGS. 2 or 5, in such a manner that themarginal portion 42 of one element is superposed on the marginal portion41 lower in level than the adjacent element, and then maybe rigidlysecured on the foundation D by having nails N or clamps threaded throughthe registered perforations 43 and fastened to the foundation D. Torigidly secure the elements 10-30 on the foundation D, any suitablebonding agent (not shown) may be injected into the `registeredperforations 43 until the same reaches the foundation D. Alternatively,any suitable bonding agent may be applied to either the lower surfacesof the marginal portions 41 and 42 or the upper surface of thefoundation D. If desired, any desired combination of the processes justdescribed may be utilized.

The marginal portions 41 and 42 superposed in the manner as abovedescribed are advantageous in that the nails or clamps, if used, arefewer in number as compared with the case in which the marginal portionsabut against each other without being superposed and that any excessiveforce which might be externally applied to the element will effectseparation of the element from the foundation only with difficulty ascompared with the case where the elements are independently mounted onthe foundation.

Referring now to FIG. 5 of the drawings, there is illustrated a mannerin which a ski is straight sliding along the artificial Gelande composedof the elements of the invention. As shown in FIG. 5, a ski or Sledge Shas its bottom surface substantially parallel to the base sheets andbrought in contact with the free extremities of the longer needle-likeprojections 31 which, in turn, are somewhat curved. However, the bottomsurface of the ski S is not put in contact with the shorter needle-likeprojections 32. Under these circumstances, a skier can effect straightsliding movement on the artificial Gelande with a relatively lowfrictional resistance resulting in an increase in straight slidingvelocity.

FIG. 6 illustrates a ski S extending substantially perpendicularly tothe plane of the figure and tilted laterally. As shown, the bottomsurface of the ski S is brought in contact with not only the longerneedle-like projections 31 but also the shorter projections 32 resultingin an increase in frictional resistance. Therefore, the ski S is subjectto a high braking force.

If the shorter needle-like projections 32 are made thinner than thelonger needle-like projections 31, the element increases its exibilityor pliability. Under these circumstances, if a skier desires to changefrom straight sliding movement to braking movement, he can very smoothlybrake as he would do on a natural snow layer but would not be subject toan abruptly increased resistance leading to his falling forwardly.

Referring now to FIG. 7 wherein the same reference numerals designatesimilar components to those illustrated in FIGS. 1 through 4, there isillustarted a modification of the invention. The modificationillustrated includes a base sheet 10` identical to that previouslydescribed in conjunction with FIGS. 1 through 4 and a needle unit 30consisting of a multiplicity of needle-like projections similar to thosealready described for FIGS. 1 through 4 excepting that the needle-likeprojections each have on the free end portion a at rough surface 33. Dueto a high frictional resistance between the rough end surfaces 33 of theneedle-like projections and a bottom surface of a ski moving thereon, askier is prevented from sliding down at a high speed along the Gelandecomposed of such elements. Thus the elements illustrated in FIG. 7 canCompose a Gelande suitable for be ginners.

FIG. 8 illustrates an arrangement similar to FIG. 7 excepting that eachof needle-like porjections is provided on the upper end portion with arecess or well 34 in place of the upper rough end surface 33 shown inFIG. 7. The well 34 serves to increase the fiexibility or pliability ofthat portion of the needle-like projection surrounding the well and alsoexhibits a cushion effect due to the air confined by the well. Thiscushion effect serves to decrease the frictional resistance between theupper ends of the needle-like projections and a ski moving thereonthereby to increase the sliding speed of the ski.

In FIG. 9 there is illustarted another modification of the structuralelement according to the teachings of the invention wherein theneedle-like projections are of a hollow type. As shown, each ofneedle-like projections includes a wall 35 and an axial hollow space 36confined by the wall, closed at the upper end and opening on the bottomface of a base sheet 10'. By providing the hollow space 36, theneedle-like projection can increase its flexibility and also its wall 35can be made uniformly thin regardless of the outside diameter of theprojection. In addition, the material for the structural element can notonly be greatly saved but also the cushion effect can be enhanced due tothe air confined by the hollow portion 36 having its lower end closed bythe associated portion of a foundation D.

What I claim is:

1. A structural element for use in constructing an artificial slide forskiing, comprising a base sheet having projecting from one face thereofa plurality of exible needle-like projections and having peripheralmargins therearound which are free of needle-like projections, saidmargins being for connecting the element with an adjacent element, saidbase sheet and said plurality of needlelike projections beingthermoplastic resinous material, and said plurality of needle-likeprojections being in at least two groups, the needle-like projections ofone group having a greater height than the projections in the othergroup, and individual needle-like projections of each group beingpositioned alternately with the individual needles of the other group,the needle-like projections being in rows extending in longitudinal,transverse and oblique directions on the said one face of said basesheet.

2. A structural element as claimed in claim 1, wherein each of saidneedle-like projections has a rough surface on the upper free endthereof.

3. A structural element as claimed in claim 1, wherein each of saidneedle-like projections has a recess in the upper free end thereof.

4. A structural element as claimed in claim 1, wherein each of saidneedle-like projections has a longitudinal hollow portion closed at theupper end and opening at the lower end out of the lower face of saidbase sheet.

5. A structural element as claimed in claim 1 wherein said base sheethas on said one face from which said multiplicity of needle-likeprojections extend a plurality of ribs composed of the samethermoplastic resinous material and formed integrally on said one facethereof and from which ribs at least some ofthe needle-like projectionsof said plurality of needle-like projections extend.

References Cited UNITED sTATEs PATENTS 2,174,716 10/1939 Betheu 272-5653,047,291 7/1962 Hau 272-565 3,078,490 2/1963 Etcher 15-216 3,224,76312/1965 Han 272-565 3,233,893 2/1966 Meyer 272-565 RICHARD C. PINKHAM,Prima/'y Examiner.

ANTON O. OECHSLE, Examiner.

A. W. KRAMER, Assistant Examiner.

1. A STRUCTURAL ELEMENT FOR USE IN CONSTRUCTING AN ARTIFICIAL SLIDE FORSKIING, COMPRISING A BASE SHEET HAVING PROJECTING FROM ONE FACE THEREOFA PLURALITY OF FLEXIBLE NEEDLE-LIKE PROJECTIONS AND HAVING PERIPHERALMARGINS THEREAROUND WHICH ARE FREE OF NEEDLE-LIKE PROJECTIONS, SAIDMARGINS BEING FOR CONNECTING THE ELEMENT WITH AN ADJACENT ELEMENT, SAIDBASE SHEET AND SAID PLURALITY OF NEEDLELIKE PROJECTIONS BEINGTHERMOPLASTIC RESINOUS MATERIAL, AND SAID PLURALITY OF NEEDLE-LIKEPROJECTIONS BEING IN AT LEAST TWO GROUPS, THE NEEDLE-LIKE PROJECTIONS OFONE GROUP HAVING A GREATER HEIGHT THAN THE PROJECTIONS IN THE OTHERGROUP, AND INDIVIDUAL NEEDLE-LIKE PROJECTIONS OF EACH GROUP BEINGPOSITIONED ALTERNATELY WITH THE INDIVIDUAL